Pair Production does not occur in free space, regardless of the energy of the photon(s) that transit through that space. The DPs simply respond by separating and orientating in accord with the photonic E and B fields. Space conducts the photonic energy at the rate dictated by the electrical (capacitive – ) and magnetic (inductive – ) properties of the space. As long as there is no charged mass (such as a heavy nucleus which will produce electron-positron pairs from rays) to distort the photon and break its internal integrity, space can conduct photons with the highest possible energy without breaking into pairs of matter-antimatter particles.